Annular combustor for a gas turbine engine

ABSTRACT

A segmented annular combustor for a gas turbine engine, axially extending between a first axial burner end and a second axial outlet end and radially extending between an annular inner liner and an annular outer liner, wherein the annular combustor is at least an assembly of: a first part including the annular inner liner and a first connection element for connecting the first part to the gas turbine engine, a second part including the annular outer liner and a second connection element for connecting the second part to the gas turbine engine independently from the first part, the second part being attachable to the first part in a removable way, at least one of the first connection element and of the second connection element being adjacent to the outlet end of the combustor.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the US National Stage of International ApplicationNo. PCT/EP2016/056793 filed Mar 29, 2016, and claims the benefitthereof. The International Application claims the benefit of EuropeanApplication No. EP15162999 filed Apr 9, 2015. All of the applicationsare incorporated by reference herein in their entirety.

FIELD OF INVENTION

The present invention relates to an annular combustor for a gas turbineengine and to a gas turbine engine including such a combustor.

ART BACKGROUND

Annular combustors are well known in the field of gas turbine engines.

An annular combustor is normally included in a gas turbine engine 1comprising, arranged in flow series: a compressor section, a burner, theannular combustor and a gas turbine section. In operation of the gasturbine engine, air is compressed by the compressor section anddelivered to the combustion section, including the burner and theannular combustor. The compressed air exiting from the compressor entersthe burner, where is mixed with a gaseous or liquid fuel. The air/fuelmixture is then burned and the combustion gas from the combustion ischannelled through the combustor to the gas turbine section, fortransforming the energy from the operative gas into working power.

The annular combustor for the above described application normallyextends axially between a first axial burner end, close to the burnerand a second axial outlet end, adjacent to the inlet of the gas turbinesection. Further the annular combustor radially extends between anannular inner liner and an annular outer liner. At first axial burnerend, the annular combustor comprises an annular backwall for connectingthe annular inner liner and the annular outer liner. The backwallcomprises at least a hole for coupling at least a respective burner tothe annular combustor.

According to a known possible prior art solution, the annular combustordescribed above is normally manufactured in one piece including at leastthe annular inner liner, the annular outer liner and the backwall. Suchunitary piece is then attached to the gas turbine engine by means of oneor more connections provided between the combustor and a casing of thegas turbine engine. Such a connection is typically remote from theinterface between the outlet of the combustor and the inlet of the gasturbine, therefore a gap is necessary between the combustor and the gasturbine for allowing thermal expansions.

Such an annular combustor and attachment determines a plurality ofinconveniences:—the gap in the interface between the combustor and theinlet of the turbine section cannot be reduced below a lower limit. Thisleads to damages to the components, due to hot gas ingestion, i.e. thehot gas exiting the second axial outlet end of the combustor and leakingthrough the gap between combustor and gas turbine section;—when areparation is required, repairing an annular combustor like the onedescribed above, i.e. a combustor manufactured in a unitary pieceattached to the casing of the gas turbine engine, is expensive.

Prior art solutions to above inconveniences may be,respectively:—purging air has in the cavity between the combustor andthe gas turbine section;—cutting the combustor into several pieces,that, after reparation, have nevertheless to be welded back together.

The above solutions are not yet considered optimal and therefore it isstill desirable to provide a new annular combustor design forefficiently overcoming the above described drawbacks.

SUMMARY OF THE INVENTION

It may be an object of the present invention to provide an annularcombustor for a gas turbine engine permitting to reduce at the minimumor eliminating the gap between the combustor and the inlet of theturbine section, in such a way that the phenomenon of hot gas ingestionis avoided or limited to a minimum.

It may be a further object of the present invention to provide anannular combustor for a gas turbine engine, whose maintenance is easierand less expensive, with respect to the prior art.

It may be an additional object of the present invention to provide a gasturbine engine including an annular combustor having a reduced gapbetween the combustor and the inlet of the turbine section and whosemaintenance is easier and less expensive, with respect to the prior art.

In order to achieve the objects defined above, an annular combustor fora gas turbine is provided in accordance with the independent claim. Thedependent claims describe advantageous developments and modifications ofthe invention.

According to a first aspect of the present invention, a segmentedannular combustor for a gas turbine engine, the annular combustoraxially extending between a first axial burner end and a second axialoutlet end, the annular combustor radially extending between an annularinner liner and an annular outer liner, the annular combustor being atleast an assembly of:—a first part including the annular inner liner anda first connection element for connecting the first part to the gasturbine engine,—a second part including the annular outer liner and asecond connection element for connecting the second part to the gasturbine engine independently from the first part, the second part beingattachable to the first part in a removable way,—at least one of thefirst connection element and of the second connection element beingadjacent to the outlet end of the combustor.

The segmentation of the annular combustor allows reducing at the minimumor eliminating the gap between the outlet of the combustor and the inletof the gas turbine. As a result, hot gas ingestion is eliminated oreffectively reduced, thus producing a much more robust design, whichwould be also easier and therefore cheaper to repair. In particular,with the design of the present invention, it is also possible to replaceonly a certain part of the combustor (for example only the inner lineror only the outer liner) on site, because no cutting and welding wouldbe needed.

Further, reducing the slot between the combustor and the turbine makesit possible to improve the flow path aerodynamics of the transitionbetween combustor and turbine.

The term “segmented” means that the combustor is not a single unitarypiece but an arrangement of segments.

According to an exemplary embodiment of the present invention, the firstor the second part further includes a backwall for connecting theannular inner liner and the annular outer liner at the first axialburner end, the backwall comprising at least an hole for coupling aburner to the annular combustor.

According to another exemplary embodiment of the present invention, theannular combustor is an assembly of the first part, the second part, andat least a third part including:—a backwall for connecting the annularinner liner and the annular outer liner at the first axial burner end,the backwall providing at least an hole for letting a gas including fueland air inside the annular combustor,—a third connection element forconnecting the third part to a casing of the gas turbine engine.

According to the last two described embodiments, it is either possiblethat the annular combustor of the present invention is made part of twoparts, one including the backwall, or is made of three parts,respectively including inner liner, outer liner and backwall.Advantageously, these variants give the possibility to adapt thecombustor design of the present invention to the design of different gasturbine engines, for example gas turbine engines having differentoverall dimensions.

According to a further embodiment of the present invention, between thebackwall and at least one of the inner liner and the annular outer linera sealing is provided.

More particularly, the sealing may comprise at least a finger seal.

The sealing avoids leakages through the contacts between first, secondand third part of the annular combustor at the backwall, i.e. where thefirst, second and third part contact each other.

According to another exemplary embodiment of the present invention, theannular inner liner and/or the annular outer liner comprise a pluralityof effusion holes for letting compressed air to enter the combustorthrough the annular inner liner and /or the outer liner, in order tocool the annular inner liner and /or the outer liner, respectively.

According to yet another exemplary embodiment of the present invention,the annular inner liner and/or the annular outer liner comprises atleast a cooling passage inside the liner.

The cooling passage may be provided between two panels of the annularinner liner and/or of the annular outer liner, bonded together.

The effusion holes or the cooling passages provide the necessary coolingto the walls of the inner and outer liners.

According to a second aspect of the present invention, a gas turbineengine comprises a burner, a gas turbine and an annular combustor asabove described, between the burner and the gas turbine.

According to a third aspect of the present invention, a gas turbinecomprises an inlet section and at least one connection element adjacentto the inlet section for coupling with an annular combustor as abovedescribed.

BRIEF DESCRIPTION OF THE DRAWINGS

The aspects defined above and further aspects of the present inventionare apparent from the examples of embodiment to be described hereinafterand are explained with reference to the examples of embodiment. Theinvention will be described in more detail hereinafter with reference toexamples of embodiment but to which the invention is not limited.

FIG. 1 is a partial schematic view, sectioned along a longitudinaldirection, of a gas turbine engine including a first embodiment of anannular combustor according to the present invention,

FIG. 2 is a partial schematic view, sectioned along a longitudinaldirection, of a gas turbine engine including a second embodiment of anannular combustor according to the present invention,

FIG. 3 is a partial schematic view, sectioned along a longitudinaldirection, of a gas turbine engine including a third embodiment of anannular combustor according to the present invention,

FIG. 4 is a partial schematic view, sectioned along a longitudinaldirection, of a gas turbine engine including a fourth embodiment of anannular combustor according to the present invention,

FIG. 5 shows a magnified view of the detail V of FIG. 4.

DETAILED DESCRIPTION

Hereinafter, above-mentioned and other features of the present inventionare described in details. Various embodiments are described withreference to the drawings, wherein the same reference numerals are usedto refer to the same elements throughout. The illustrated embodimentsare intended to explain, and not to limit the invention.

FIG. 1 shows an example of a gas turbine engine 1 in a partial schematicsectional view.

The gas turbine engine 1 (not shown as a whole) comprises, in flowseries, a compressor section 4 (not shown as a whole), a plurality ofburners 2 (only one burner 2 shown in each of the section FIGS. 1 to 4)an annular combustor 10 and a gas turbine 3, which are generallyarranged in flow series within a casing 5.

The gas turbine engine 1 is generally arranged about a rotational axisX, which is the rotational axis for rotating components, in particularthe compressor section 4 and the gas turbine 3. The rotational axis X isalso coincident with the axis of symmetry of the annular combustor 10,when the annular combustor 10 is assembled to the gas turbine engine 1.

In operation of the gas turbine engine 1, air is compressed by thecompressor section 4 and delivered to the combustion section, includingthe burner 2 and the annular combustor 10. The compressed air exitingfrom the compressor 4 and flowing towards the combustion section isschematically represented in the attached figures by arrows A. Thecompressed air enters the burner 2 where is mixed with a gaseous orliquid fuel. The air/fuel mixture is then burned and the combustion gasfrom the combustion is channelled through the combustion chamber 10 tothe gas turbine section 1, for transforming the energy from theoperative gas into working power. The combustion gas flows along thecombustion chamber 10 along a main direction oriented from the burner 2to the gas turbine 3.

The combustion section 4 and the burner 2 are not a specific object ofthe present invention and, therefore, in the following, they will not bedescribed in further detail. In the following the terms radial,circumferential and axial are with respect to the rotational andsymmetry axis X.

The annular combustor 10 extends axially between a first axial burnerend 11 and a second axial outlet end 12 and radially between an annularinner liner 15 and an annular outer liner 16.

The annular combustor 10 further includes: - a first part 21 includingthe annular inner liner 15 and a first connection element 31 forconnecting the first part 21 to the gas turbine engine 1,—a second part22, distinct from first part 21, including the annular outer liner 16and a second connection element 32 for connecting the second part 22 tothe gas turbine engine 1,—a backwall 25 for connecting the annular innerliner 15 and the annular outer liner 16 at the first axial burner end11. The backwall 25 comprises a plurality of holes 26, distributed aboutthe axis X, for coupling a plurality of respective burners 2 to theannular combustor 10.

According with the different embodiments of the present invention, atleast one of the first connection element 31 and of the secondconnection element 32 is adjacent to the outlet end 12 of the combustor10 and is connectable to a respective gas turbine connection element 17,18 on the gas turbine 3, respectively radially inner and outer. Theconnection elements 17, 18 are adjacent to the inlet section 13 of thegas turbine 3.

Optionally, the annular combustor 10 further comprises a third part 23,distinct from first part 21 and from the second part 22. The third part23 includes the backwall 25 and a third connection element 33 forconnecting the third part 22 to the casing 5 of the gas turbine engine1.

With reference to the embodiment of FIG. 1, the annular combustor 10 isan assembly of:—the first part 21, with the first connection element 31connecting the first part 21 to the inner connection element 17 of thegas turbine 3,—the second part 22, with the second connection element 32connecting the second part 22 to the outer connection element 18 of thegas turbine 3, —the third part 23, with the third connection element 33connecting the third part 23 to a casing connection element 35 on thecasing 5.

The coupling between the first, second and third part 21, 22, 23 and thegas turbine 3 and the casing 5, respectively, is circumferentiallydistributed about the axis X. According to the different embodiments ofthe present invention, this may be obtained with circumferentialelongated connection elements 31, 32, 33, 17, 18, 35. As an alternativeeach of the first part 21, second part 22 and third part 23 comprises arespective plurality of connection elements 31, 32, 33 to be coupled toa respective plurality of connection elements 17, 18 on the gas turbine3 and of connection elements 35 on the casing 5.

With reference to the embodiment of FIGS. 2 and 3, the third part 23 isnot present and the backwall 25 is comprised in the first part 21 and inthe second part 22, respectively.

The annular combustor 10 of FIG. 2 is therefore an assembly of:—thefirst part 21, including the annular inner liner 15 and the backwall 25,with the first connection element 31 connecting the first part 21 to thecasing connection element 35,—the second part 22, with the secondconnection element 32 connecting the second part 22 to the outerconnection element 18 of the gas turbine 3.

The coupling between the first and the second part 21, 22 and the casingand 5 the gas turbine 3, respectively, is circumferentially distributedabout the axis X. According to the different embodiments of the presentinvention, this may be obtained with circumferential elongatedconnection elements 31, 32, 18, 35. As an alternative each of the firstpart 21 and second part 22 comprises a respective plurality ofconnection elements 31, 32 to be coupled to a respective plurality ofcasing connection elements 35 and of outer connection elements 18 on thegas turbine 3.

The annular combustor 10 of FIG. 3 is instead an assembly of:—the firstpart 21, with the first connection element 31 connecting the first part21 to the inner connection element 17 of the gas turbine 3,—the secondpart 22, including the annular outer liner 16 and the backwall 25, withthe second connection element 32 connecting the second part 22 to thecasing connection element 35.

The coupling between the first and the second part 21, 22 and the gasturbine 3 and the casing 5, respectively, is circumferentiallydistributed about the axis X. According to the different embodiments ofthe present invention, this may be obtained with circumferentialelongated connection elements 31, 32, 17, 35. As an alternative each ofthe first part 21 and second part 22 comprises a respective plurality ofconnection elements 31, 32 to be coupled to a respective plurality ofinner connection elements 17 on the gas turbine 3 and of casingconnection elements 35.

In all the embodiments above described, the couplings between the first,second and third part 21, 22, 23 and the gas turbine 3 and/or the casing5 are detachable and may performed by means of screw (or other threadedconnection) and/or bolts. This allows connecting and disconnecting eachpart 21, 22, 23 of the annular combustor 10 independently from theothers.

In all embodiments, the mounting of the first, second and third part 21,22, 23 in the gas turbine engine is made in such a way that the outletend 12 of the annular combustor 10 is mounted adjacent to the inletsection 13 of the gas turbine 3. This avoids or limits hot gas leakageswhen hot gases from the annular combustor 10 enter the gas turbine 3.

In all the embodiments of the present invention the annular combustor 10is constituted as an assembly of two (embodiments of FIGS. 2 and 3) orthree (embodiments of FIGS. 1 and 4) main parts 21, 22, 23 attachable toeach other in a removable way, in order that each of the two or threeparts 21, 22, 23 of the annular combustor 10 is connectable anddisconnectable to the gas turbine 3 and/or the casing 5 independentlyfrom the other(s) of the parts 21, 22, 23 of the annular combustor 10.

This implies no permanent connection, for example a welded connection,is provided between the two or three main parts 21, 22, 23 whichconstitutes the annular combustor 10.

The first, second and third part 21, 22, 23 contact each other along theedges of the backwall 25. To avoid leakages through the contacts betweenfirst, second and third part 21, 22, 23, a sealing 40 is providedbetween the backwall 25 and at least one of the inner liner 15 and theannular outer liner 16.

In the embodiments of the attached FIGS. 1 to 4, the sealing 40comprises an inner finger seal 41 between the backwall 25 and the innerliner 15 and/or an outer finger seal 42 between the backwall 25 and theouter liner 16.

In the embodiment of FIGS. 1 and 4, where the first, second and thirdpart 21, 22, 23 are present, both the inner and outer finger seals 41,42 are present.

In the embodiment of FIG. 2, where the backwall 25 is integrated in thefirst part 21 of the annular combustor 10, only the outer finger seal 42is present.

In the embodiment of FIG. 3, where the backwall 25 is integrated in thesecond part 22 of the annular combustor 10, only the inner finger seal41 is present.

According to other embodiments of the present invention, other sealingdevices may be used between the parts 21, 22, 23 of the annularcombustor 10, in order to avoid hot gas leakages between the backw all25 and the inner liner 15 and/or between the backwall 25 and the outerliner 16.

The inner finger seal 41 and/or the outer finger seal 42 interact withthe third part 23 such that the first part 21 and/or the second part 22engage with another slidably. In fact the finger seal 41 and/or theouter finger seal 42 protrude in a corresponding depression of the thirdpart 23. This allows for thermal expansion and/or to counteractmechanical stress which otherwise could occur. By this finger sealconfiguration the second part 22 is attachable to the first part 21—viathe third part 23—in a removable way.

In other words, the first part 21 is removably attachable to the thirdpart 23 and/or the second part 22 is removably attachable to the thirdpart 23.

In the embodiment of FIGS. 1 to 3, the annular inner liner 15 and theannular outer liner 16 comprise a plurality of effusion holes 50 forletting compressed air (represented by arrows A) to enter the combustor1) through the walls of the annular inner liner 15 and the outer liner16, in order to cool the annular liners 15 and 16, respectively.

The embodiment of FIG. 4 is similar to the embodiment of FIG. 1, i.e itcomprises the first, second and third parts 21, 22, 23 of the annularcombustor independently attached to the gas turbine 3 and to the casing5. The embodiment of FIG. 4 is different from the embodiment of FIG. 1for the fact that the annular inner liner 15 and the annular outer liner16 comprises one or more cooling passages 60 inside the respective liner15, 16, for providing cooling by letting a flow of compressed air Aenter the annular combustor 10 through the cooling passages 60. Eachcooling passage 60 is obtained inside the walls of the annular innerliner 15 and the annular outer liner 16 by means of at least two panels61, 62, respectively internal (i.e. facing the inner volume of thecombustor 10, where hot gasses flow) and external (i.e. facing a volumeexternal to the combustor 10, where compressed air A from the compressor4 flows). Each cooling passage 60 comprises an inlet 63, through whichcompressed air A enters the passage 60, and an outlet 64, through whichcompressed air A exits the passage 60 to enter the annular combustor 10.

According to other embodiments (not shown) of the present invention,mixed solutions are possible:—the annular liners 15, 16 comprise botheffusion holes 50 and cooling passages 60, for example on differentzones of the annular liners 15, 16,—one of the annular liners 15, 16comprises effusion holes 50, while the other comprises cooling passages60.

To summarize previous sections, the combustor is not one large singularcomponent but is split up into two or three parts, i.e. the combustor isa segmented combustor. This is achieved by mounting/suspending thebackwall and liners individually. The liners can be mounted/suspended toa turbine module and a backwall to a central casing. One alternative iswhere the outer liner and the backwall are one component whilst theinner liner remains separate, see FIG. 3. This would allow eliminationof even more parts compared to a previous combustor design but will meanthat the backwall will move due to thermal expansion in relation to theburner which can also be disadvantageous.

Due to the segmented approach different parts could berepaired/exchanged individually and disassembling the combustor would bea lot easier.

When the liners and the backwall/heat shield can move individually theinterface between them become of importance. Leakage between liners andbackwall is controlled using a seal design. This could be achieved usingfinger seals as demonstrated for example in FIG. 1 or 4.

Bolting the liners to the turbine module could make it much easier tocontrol the interface between combustor and turbine. Also reducing theslot between the combustor and turbine makes it possible to improve theflow path aerodynamics of the transition between the combustor andturbine.

Repair would be made a lot easier and therefore also cheaper. It wouldalso become possible to replace only a certain part (inner liner/outerliner/backwall) on site because no cutting and welding would be needed.

1. A segmented annular combustor for a gas turbine engine, the annularcombustor axially extending between a first axial burner end and asecond axial outlet end, the annular combustor radially extendingbetween an annular inner liner and an annular outer liner, the annularcombustor comprising: an assembly of: a first part including the annularinner liner and a first connection element for connecting the first partto the gas turbine engine, a second part including the annular outerliner and a second connection element for connecting the second part tothe gas turbine engine independently from the first part, the secondpart being attachable to the first part in a removable way, wherein atleast one of the first connection element and of the second connectionelement being adjacent to the outlet end of the combustor.
 2. Thecombustor according to claim 1, wherein the first or the second partfurther includes a backwall for connecting the annular inner liner andthe annular outer liner at the first axial burner end, the backwallcomprising at least an hole for coupling a burner to the annularcombustor.
 3. The combustor according to claim 1, wherein the annularcombustor is an assembly of the first part, the second part, and atleast a third part including: a backwall for connecting the annularinner liner and the annular outer liner at the first axial burner end,the backwall providing at least an hole for letting a gas including fueland air inside the annular combustor, a third connection element forconnecting the third part to a casing of the gas turbine engine.
 4. Thecombustor according to claim 2, wherein between the backwall and atleast one of the inner liner and the annular outer liner a sealing isprovided.
 5. The combustor according to claim 4, wherein the sealingcomprises at least a finger seal.
 6. The combustor according to claim 2,the annular inner liner and/or the annular outer liner comprise aplurality of effusion holes for letting compressed air to enter thecombustor through the annular inner liner and/or the outer liner, inorder to cool the annular inner liner and /or the outer liner,respectively.
 7. The combustor according to claim 2, the annular innerliner and/or the annular outer liner comprises at least a coolingpassage inside the liner.
 8. The combustor according to claim 7, whereinthe cooling passage is provided between two panels of the annular innerliner and/or of the annular outer liner, bonded together.
 9. A gasturbine engine comprising: a compressor, a gas turbine, a burner, and asegmented annular combustor according to claim 1, between the burner andthe gas turbine.
 10. The gas turbine engine according to claim 9,further comprising: an inlet section and at least one connection elementadjacent to the inlet section for coupling with at least one of thefirst connection element and the second connection element of theannular combustor.
 11. The gas turbine engine according to claim 9,further comprising: a casing with a further connection element forcoupling with one of the first or second or the third connection elementof the annular combustor.
 12. The gas turbine engine according to claim10, wherein at least one of said couplings of the first, second or thirdconnection element is of the threaded type.
 13. The gas turbine engineaccording to claim 9, wherein the outlet end of the annular combustor ismounted adjacent to the inlet section for avoiding or limiting leakagesof hot gases when hot gases from the annular combustor enters the gasturbine.
 14. A gas turbine for a gas turbine engine comprising: an inletsection and at least one connection element adjacent to the inletsection for coupling with at least one of the first connection elementand the second connection element of an annular combustor according toclaim 1.